The polycarbonate ophthalmic lens owes a debt to the compact disc. That's because PC prescription lenses only became feasible after the CD market pushed resin suppliers to develop an ultrapure PC for injection molding CD-ROMs and music CDs, said Jon Haglund, chairman and chief executive at Neolens Inc., a PC lens molder in Miami.
With quality no longer an issue, the PC ophthalmic lens business took off, Haglund said in a recent telephone interview.
``If you go into our warehouse, the bags of material that we use say CD resin,'' he noted.
In fact, all four factors driving PC lens growth have to do with the material's properties, said Mike Hawks, chief financial officer at BMC Industries Inc. PC, already lightweight, has a high refractive index, which means it also can be ground very thin, so people with very strong prescriptions do not need to wear very thick lenses.
``All clear materials have an index of refraction,'' explained Joe Bruneni, who heads up the Polycarbonate Lens Council.
Glass and PPG Industries Inc.'s CR-39, an allyl diglycol carbonate, are ``relatively close,'' having indexes of 1.52 and 1.50, respectively, he said. But PC, with an index of 1.59, is the best of the high-index materials, he added.
PC also blocks ultraviolet light: ``If it didn't have UV inhibitor built into it at the time it was created, it would degrade under sunlight,'' Bruneni said.
And the material is shatterproof, making it safer than other optic materials, particularly for children's eyewear.
``It's a natural for children,'' said Gary Roderick, marketing manager for Gentex Optics Inc. ``That's still where a good chunk of [the PC lens market] is disposed,'' roughly 40 percent, he said.
And though sports eyeware, sun and safety glasses make up another good piece of business, adult prescription PC lenses are growing the most now, he said.
Ease of manufacturing also has contributed to the PC segment's success. The injection molded material's main market competitor is CR-39, a thermoset plastic. CR-39 lenses are cast by pouring monomer into two molds held together by a gasket, then curing it in water or heat for about 16 hours to take it from a liquid to a solid state, according to PPG's Ralph Kent, who manages market development of optical products.
One industry source said that a factory making CR-39 lenses with a capacity of 2 million pairs of lenses might require as many as 400 employees, compared with the 50 workers needed to operate the same capacity at a PC injection molding plant.
The only drawback to PC is its softness, said Justus Homburg, director of business development at Monsanto Co.
``[The PC lens] has all these wonderful characteristics, except for one: If you even look at it, it starts to scratch,'' Homburg said.
Haglund said the PC lens market's slowness at developing scratch-resistant coatings was another factor that held back growth. But that is no longer the case, he said, noting that Neolens has its own coating technology.
Monsanto's strategy in acquiring Orcolite was to marry the Azusa, Calif., company's PC lenses to scratch-resistant coatings made by Monsanto's Diamonex unit in Allentown, Pa., Homburg said. He claims the Diamonex coating does a better job than conventional methods, such as silicone dips.
``It makes PC perform as though it's as hard, if not harder than, glass,'' he said.
The only snag now is the dispenser at the retail level, who may harbor leftover suspicions about the quality of the material, Roderick said. But gradually those labs are being educated by people like Bruneni, who was hired by the PC lens council seven years ago to head that trade group's marketing efforts when PC began to attract ophthalmic interest.
Bruneni compared PC's rise to that of CR-39, when nearly 50 years ago it began to be used in lenses. He summed it up this way: ``The plastic lens came in slowly ... and now dominates the U.S. market.''
Roderick took that thought further. With no obstacles in its way, PC will keep making inroads into the ophthalmic lens market - some day replacing CR-39, as CR-39 virtually has replaced glass, he said.